Hard to understand; difficult to grasp because something (an explanation, text, situation) is unclear or complicated.
この説明は専門用語が多くてわかりにくい。
This explanation has a lot of technical terms and is hard to understand.
字が小さくてポスターの注意書きがわかりにくい。
The letters are small, so the warning on the poster is difficult to read/understand.
彼の話し方は早口で、重要な点がわかりにくい。
He speaks quickly, so the important points are hard to follow.
このプログラムの使い方は初心者にとってわかりにくいかもしれない。
The way to use this program might be hard to understand for beginners.